Fiqh-us-Sunnah Volume 1, Purification and Prayer, Fiqh 1.007.

Section : Dead animals of the sea and dead locusts.

Ibn ‘Umar reported that the Messenger of Allah said, “Two types of dead animals and two types of blood have been made lawful for us. The types of dead animals are seafood and locusts. The two types of blood are the (blood of the) liver and the spleen.”

This is related by Ahmad, ash-Shaf’i, al-Baihaqi and adDaraqutni. The hadith is weak, but Imam Ahmad says that it is authentic in mauqoof form. Abu Zar’ah and Abu Hatim have said the same. Such a report has the implication of a marfu’  hadith because a companion saying, “This was allowed for us” or “This was forbidden for us” is like one of them saying, “We were ordered to do this,” or “We were forbidden to do this,” and so on. (Such statements are considered marfu’ with respect to their regulations). And we have already mentioned the Prophet’s statement concerning the ocean, “Its water is pure and its ‘dead animals’ are allowable (to eat.).”